This invention relates to a passenger conveyor guide arrangement and, more particularly, to a passenger conveyor guide arrangement for guiding step rollers mounted to the side of steps of the passenger conveyor.
FIG. 1 is a schematic diagram illustrating a conventional passenger conveyor guide arrangement, FIG. 2 is a sectional view taken along line II--II of FIG. 1, and FIG. 3 is a sectional view taken along line III--III of FIG. 2. In these figures, a main frame 1 of the passenger conveyor extends between the upper landing and the lower landing. The passenger conveyor comprises an upper sprocket wheel 2 mounted on the upper end portion of the main frame 1 and driven by a drive unit 3, and a lower sprocket wheel 4 mounted on the lower end portion of the main frame 1. A step chain 5 is wound around and extended between the upper sprocket wheel 2 and the lower sprocket wheel 4 to form an endless loop and a plurality of steps 6 are connected to the step chain 5.
As shown in FIGS. 2 and 3, an axle 8 is connected to the step chain 5, and leading step rollers 7a and 7b are mounted on the opposite ends of this axle 8 extending transversely at the front portion of the step 6. The step 6 also has at the opposite sides of its rear portion trailing step rollers 9a and 9b. In order to guide and support the leading step rollers 7a and 7b, guide rails 10a and 10b of a U-shaped cross section are fixedly mounted to the conveyor main frame 1 by bolts 11a and 11b. Additional guide rails 12a and 12b of an L-shaped cross section for supporting and guiding the trailing step rollers 9a and 9b are also secured to the main frame 1 by welding.
With the passenger conveyor constructed as described above, when the drive unit 3 drives the sprocket wheel 2, the endless step chain 5 wound around the upper sprocket wheel 2 and the lower sprocket wheel 4 is driven together with the plurality of steps 6 connected to the step chain 5, and the steps 6 are guided and moved along the stairway defined by the guide rails 10a, 10b and 12a, 12b, so that the passengers on the steps can be conveyed along the stairway.
As is well known, each of the steps 6 are provided at the sides of their front portions with the leading step rollers 7a and 7b mounted on the axle 8 and at the sides of their rear portions with the trailing step rollers 9a and 9b, and they roll along and are guided by the guide rails 10a, 10b and 12a, 12b. Therefore, the steps 6 are moved and guided along the guide rails 10a, 10b and 12a, 12b.
However, in the conventional passenger conveyor guide arrangement as described above, the guide rails 10a and 10b are secured to the frame by the bolts 11a and 11b. The bolts 11a and 11b are welded at one end thereof to the bottom surfaces of the bight portions of the guide rails 10a and 10b, and the other end extends through holes in a horizontal member of the main frame 1 and are fastened thereto by nuts. Therefore, during the welding operation, the guide rails 10a and 10b are subjected to weld distortions, reducing the dimensional accuracy of the guide rails 10a and 10b.
In order to solve the above-discussed problem, an arrangement as shown in FIGS. 4 and 5 has been proposed in Japanese Utility Model Laid-Open No. 57-126482, for example. According to this arrangement, U-shaped clips 14 which engage at the tips of the legs of the U with the side walls of the guide rail 13 are used. Each U-shaped clip 14 has a threaded hole 15 in its bight portion through which the threaded end of the bolt 17 is engaged. The bolt 17 extends through the U-shaped bracket 16 welded to a suitable member of the main frame 1. When the bolt 17 is tightened the clip 14 is pulled toward the bracket 16 to firmly press the guide rail 13 against the bracket 16, thereby securing the guide rail 13 to the member of the main frame 1.
However, even with the above arrangement, the clip 16 can be plastically bent when the bolt 17 is tightened and the bolt 17 can sometimes loosen and then drop off. Also, since the tension of the bolt 17 compresses the side walls of the guide rail 13, the side walls of the guide rail 13 can collapse, decreasing the dimensional accuracy, and also forming irregular bumps which provide shocks or shakes to the step guide rollers, resulting in an uncomfortable ride in the passenger conveyor.